I've replaced both sets of shocks on my truck. The front ddid require a spring compressor, but the rears were so easy they were a joke: 20 minutes and I was done. Mine was TRD so it came with the Bilsteins from the factory, but they are definitely a little more subdued than the types you'd order as direct replacements from AutoZone or NAPA. The stockers are real narrow and, from my experience, a little more plush than the replacements I got later on.
As far as Rancho Vs. Monroe Vs. Bilstein, I say Bilstein. Hands down. Well worth the money. For one, they use gas instead of oil, so they stay cooler and perform better under rough treatment. Plus (and most importantly) Bilsteins come with a lifetime warranty for the original installing owner. Good stuff.
I've now put over 100K on mine and they're still going strong! <img src="/forums/images/graemlins/kewl.gif" alt="" />

I think you guys have swayed me into purchasing the bilsteins(even though i was leaning that way anyway!)
1 more question....I am able to use the stock OEM shocks with the lift I have. Does this mean stock replacement bilsteins will fit also? I know in the front they will because the spacer goes on top of the spring pack. But the rear has an added leaf, which extends the shock. Would I be better off getting a longer shock in the rear?

Again guys, thank you so much for the replies and great information. People like you are the reason why this forum is far superior to all other forums!! <img src="/forums/images/graemlins/kewl.gif" alt="" />

Cheers! <img src="/forums/images/graemlins/cheers.gif" alt="" />

If you have 2" or more lift for the rear, you'll need new longer shocks as you have the '03 truck. I have an '02, and I'm in the process of lifting the front and rear, along with new rear shocks as well.

If you have one of the newer '05+, then the longer rear shock is not needed as the stock shock is plenty for upto 3" lift.

Would the Bilstein 5100 series shock fit the rear? Or do I have to go with a completely different brand of shock?

As I recall, the different Bilsteins are each suited for broad range of travel. When I got mine, the AutoZone guy cross-referenced the size with the amount of travel in the suspension. But, I do think the 5100 Series would work (don't hold me to it, though!) <img src="/forums/images/graemlins/kewl.gif" alt="" />

I just got confirmation from the place I purchased the lift from that the 5100's will work. I'll probably go with those all around, unless someone out there can tell me for sure that the Bilstein HD's will work all the way around! <img src="/forums/images/graemlins/cheers.gif" alt="" />

You'll be fine with 5100's.

The data on the 05+ is inaccurate. Anything more than 1" of lift requires longer shocks. The stock shocks are barely long enough to utilize the full amount of travel afforded by the super flexy (read sucks azz) rear springs. Real world experience here, not what I read on the 'Net.